Help - Turn Signal/High Beam Problem w '70E Restoration

[tom1394racing]

I have completed most of the luggage compartment, lights and dash wiring on my '70E project. Everything seem to be working as expected except for the turn signals and high beams.

What works:
1. all interior and dash lights
2. emergency flashers
3. low beams
4. parking lights
5. headlight flash when pulling T/S switch back and ignition switch off
6. Left and right indicator lights when T/S moved to left and right with ignition switch off

What does not work:
1. high beams
2. turn signals

The high beams are illuminated even when the high beam switch is in the off position. The high beams are getting around 8-9 volts with the high beam switch off so there is only a slight brightening when the high beam switch is engaged.

I have swapped out the T/S switch and flasher relay with known good units from my '73 with no improvement.

I am fairly confident in the wiring as I have cross referenced my disassembly photos with the factory wiring diagram. The only discrepancy is the low beam wiring between the headlight switch and the T/S switch. The diagram (see photo) shows a yellow wire (low beams) at terminal 56 on the headlight switch that goes into the multi-pin connector and on to the flasher relay. My disassembly photos and the wiring on my '73 do not have this yellow wire on the headlight switch. Both show the yellow wire going from terminal 56 on the T/S switch through the multi-pin connector and then to the flasher relay. The T/S switch on both my '73 and the '70 have the yellow wire on the T/S switch going through a single spade connector on the switch unit before continuing to the multi pin connector (see photo). I do not understand the discrepancy.

My next step would swap out the headlight switch with another known good unit however I can't understand why that would make a difference.

Any help would be greatly appreciated.

[Lash LaRowe]

I could not find a 1970 wiring diagram, I do have a 1971 wiring diagram and own a 1972 911. On my 72, the ignition switch has to be on in order for the turn signals to work and headlights both low and high beams to operate.

So I will keep looking but thought that maybe your problem is associated with the ignition switch

Lash

[edmayo]

You may have the wires into the 3 pin plug behind the headlight installed wrong.

[tom1394racing]

Lash and Ed....Thanks for your replies.

The headlights and turn signals are supposed to function only when the key is in the on position. On my '70 project, with the key in the on position, my headlights work when I pull the headlight switch. The problems is the high beams also glow even when the high beam stalk is in the off position. I am not using the 3 prong plastic electrical fitting on the headlights, but rather have fitted the wires direct on the headlight spade fittings with ground at the top, high beams on the outside and low beams on the inside as indicated in the wiring diagram. I did remove the headlight and checked the voltage at the headlight connections and found 12 volts on the low beams and 8-9 volts on the high beams even when the high beam switch is off. I checked at the front fuse box and found the same voltage results.

Also no turn signals with the ignition switch on.

[304065]

Tom per DIN 72552 -

56a = low beam yellow wire
56b= high beam white wire
31 = ground

So. . . ground on the side, not the top.

And I highly, highly recommend that you use a pair of ice cube relays, cleverly concealed beneath the driver footboard, to switch current to your bulbs, and rely on our antique turn signal switch contacts only for the amperage required to pull in the relay contacts! You can still use the wires to the bulbs for an original appearance, so long as you are using the standard 45/55w bulbs. Disconnect the high and low wires from the fuse box and connect them to terminal 86 of the ice cube, run 85 to ground, power to 30 (through a 30 amp fuse in a dedicated fuse holder) and then 87, the normally open contact, goes to the bulb. Use a piece of ten gauge wire from the battery with the in-line fuse holder mounted close to the clamp, and run the ten gauge inside a piece of 1/4" heat shrink tubing for a second layer of anti-chafe.

This way you bypass the ancient switch-- the old engineers ran ALL the power through it (look at the change-over relay, item Nr. 50, on the SL35 diagram you have-- see how the power (30) comes from the switch contacts? In our old cars the relay only provides the change-over function, not actual switching of the power itself.

Your mileage may vary, be careful working around high voltage at risk of personal injury or property damage, etc. (Tom I know I don't have to tell you this you've forgotten more about engineering than I will ever know!)

With this fix you will have higher reliability. . .and only the concours cognoscenti will know. . . and if I see this kind of a mod, tastefully executed in a "factory" way with attention paid to things like the fuse, intelligently done. . .I might get distracted. . .

[Lash LaRowe]

Looking at the wiring diagram (1971) you would think that the problem would be with the turn signal switch or head light flasher relay which you have already swapped.
The voltage checks you made shows a reduced voltage for high beams, I'm thinking you may have a short from the low beam circuit to the high beam circuit.
Check the multiple pin connector between the turn signal switch and the flasher unit.

Also try making voltage checks for pins 56a and 56b output of the turn signal unit with the mutiple pin plug disconnected. Keep making voltage or continuity checks for the headlight problem. I would also check the fuse panel to make sure you do not have a strand of wire causing your problem.

I hope solving the headlight problem will fix the turn signal problem.

Keep in mind I'm using a 1971 wiring diagram and hope this is not causing you more problems

Lash

[tom1394racing]

John and Ed...Switching the connections on the headlights worked for the high beams...Thanks

John.....I appreciate your suggestion for reducing the load the high beam switch with the ice cube relays. I will likely incorporate them once I have the electrical fully sorted out. I am just a lowly Mechanical/Aerospace Engineer. I think electronics should work just like hydraulics.

Still no turn signals. Next step will be to trace the circuit as Lash has suggested. Somewhere, I saw a simplified hand drawn circuit for the turn signals. It was either here or on Pelican. I can't seem to resurrect it though.

[304065]

Tom-- a decade ago, I spent the time to trace out the wiring across the various light switches, SWB, LWB and one from an '84 Carrera-- hopefully this will be LESS confusing and not MORE confusing. What makes it slightly harder is that the wires that enter the light switch on the SL35 diagram are labeled 58 instead of 57, but you get the idea.

SWB: (going counterclockwise around the diagram)

30 +12v RED
57a for parking lights (common) GREY
49a to blinker unit (common for signals) BLACK/WHITE/GREEN
49L left turn signal bulb BLACK/GREEN
49R right turn signal bulb (imagine that!) BLACK/WHITE
57R right parking lamp GREY/RED
57L left parking lamp GREY/BLACK
56 common for headlights WHITE/BLACK
56b low beam YELLOW
56a high beam WHITE

LWB switch:

30 RED/WHITE
57A GREY
49A BLACK/WHITE/GREEN
49R BLACK/GREEN
49L BLACK/WHITE
57R GREY/RED
57L GREY/BLACK
56 WHITE/BLACK
56b YELLOW
56A WHITE

84 Carrera

30 Re/wt
P Grey (this is the "parking" terminal")
49a bk/wt/gn
49R bk/gn
49L bk/wt
58R gr/re
58L gr/bk
56 wt/bk
56b ye
56a wt

[tom1394racing]

I had some time this week to track down my turn signal problem. Not surprisingly, given that the flashers worked and I had ruled out the turn signal switch, the problem was the switched power source wire at the hazard switch that feeds switched power to the flasher relay. I found the wire behind the front fuse panel (not connected). I connected to fuse # 8 on the top fuse box and all works as intended.

Thanks to all who helped.

[304065]

Let there be light!